How did Jessica Simpson manage to slim down while keeping her curves? The secret is her regular workouts with celebrity trainer Harley Pasternak and following his 5 Factor Diet. The plan calls for five meals a day, with five elements per meal (protein, good fat, healthy carbs, fiber, and a sugar-free beverage).

Rockin’ Robin

Though this popular plan promises you’ll lose 21 pounds in 21 days, radio personality Robin Quivers lost nearly 25 following the Martha’s Vineyard Diet. The strict diet involves consuming juice, tea and soup and having regular colonics and spa treatments.

Oh Oprah!

For years we’ve watched Oprah’s show — and her weight. But with the help of trainer Bob Greene the talk show queen has finally found a diet that works for her. She eats a diet rich in lean protein, fruits and vegetables and limits alcohol, refined carbs and sugar. She also won’t eat close to bedtime.

Kirstie Alley

There’s nothing secret about Kirstie Alley’s weight loss: The once svelte star of ‘Cheers’ has been the face of Jenny Craig’s diet plan since 2004. Alley is said to have lost more than 55 pounds on the program. She’s even written about the experience in a book called ‘How to Lose Your Ass and Regain Your Life.’

Beyonce

Beyonce may be known for her curves, but the star has said she lost 20 pounds on the ever-trendy juice fast, the Master Cleanse, for her role in ‘Dreamgirls.’ The fad diet (also called the Maple Syrup Diet) consists of drinking a concoction of syrup, lemon juice, water and cayenne pepper.

Jennifer Aniston

When she starred on ‘Friends,’ Jennifer Aniston reportedly turned to the Zone Diet. On this plan, Jennifer would aim to have her diet consist of 40 percent carbohydrates, 30 percent protein, and 30 percent fat. The Zone’s founder claims this ratio will rev your metabolism.

Jennifer Lopez

J.Lo has said that her only diet is a strategy of eating anything she wants in moderation. However, it has been reported that when Jenny wants to drop some weight, she cuts out the carbs in a strategy similar to the Atkins Diet.

Madonna

How does a middle-aged singer with two children maintain such a phenomenal physique? In addition to punishing daily workouts, Madonna adheres to a strict macrobiotic diet, which is based on the idea that food affects health, well being, and happiness. The diet focuses on whole, unprocessed foods and is low in fat, high in fiber and rich in vegetables and soy.

Jessica Biel

To get into fighting shape for ‘Blade: Trinity,’ Jessica Biel followed a strict diet that banned sugar, dairy, flour and salt. To keep her metabolism revved up and to get her through an intense workout schedule, Jessica has said she would eat several small meals every few hours, similar to the 3-Hour Diet.

Eva Longoria is petite but fit, and she keeps her figure through kickboxing sessions. A student of kinesiology, Longoria knows how the human body responds to certain movements, and she isolates muscles by cardio training, weight training, and alternating days of yoga. To tighten her bottom, she does leg presses, squats, and lunges. Mind you, Longoria is not on any strict diet. She simply eats a lot of fresh fruits and vegetables, but she still has time for the occasional pizza slice.

Teri Hatcher is still fabulous at age forty, and she keeps her figure slim by toning her body in the sauciest, naughtiest way possible: striptease classes. Pole dancing is now being offered at many gyms all over the world: it not only teaches a woman how to isolate and tone certain muscles, but it empowers a woman because it makes her more comfortable with her body.

The average pole dancing session will entail about an hour of stretching muscles in the buttocks, arms, and chest, then half an hour of routines using the pole. Hatcher takes these classes twice or thrice a week. In addition, she plays golf and hikes regularly.